Problem In my If/Else Statements or Other part of the scripts?

Sooo i have a problem on my script

local gui = script.Parent
local Player = game.Players.LocalPlayer
local slot1 = script.Parent.s1
local slot2 = script.Parent.s2
local slot3 = script.Parent.s3
local slot4 = script.Parent.s4
local check1 = slot1.check.Value
local check2 = slot2.check.Value
local check3 = slot3.check.Value
local check4 = slot4.check.Value
while true do
local Tool1 = Player.Backpack:FindFirstChild("Key")  or Player.Character:FindFirstChild("Key")
local Tool2 = Player.Backpack:FindFirstChild("Key2")  or Player.Character:FindFirstChild("Key2")
local Tool3 = Player.Backpack:FindFirstChild("Key3")  or Player.Character:FindFirstChild("Key3")
local Tool4 = Player.Backpack:FindFirstChild("Map")  or Player.Character:FindFirstChild("Map")


if Tool1 then
    if check1 == false then
    slot1.key.Visible = true
    check1 = true
    else
        if check2 == false then
            slot2.key.Visible = true
            check2 = true
        else
            if check3 == false
            then
                slot3.key.Visible = true
                check3 = true
            else
                if check4 == false
                then
                    slot4.key.Visible = true
                    check4 = true
                else
                    print("No Space")
        end
        end
        end
        end


end
wait()
    end

So in this script, i've wanted to make a slots for tools the check1,check2,check3,check4 is a bool value that is false. So I've wanted to make when the tool1 is in your backpack the if statement will work

so if check1 is false (Empty) then slot1 will make the key icon appear but the problem is when I collect the Tool all the slots have the key icon appeared Idk how it's possible because

Else part will only run if check1.value is true but all the slots have a key icon on all of it

So basically I wanna make a Custom Inventory using these things because I still don't know how to use Tables

Note: I wanna make The Key Icon appear on an Empty slot, If Bool Value is false it means its empty but if its true it means it's not empty so it will proceed to another slot then check if its Bool Value is False but if isn't it will proceed to another slot etc.